We used an atmospheric-pressure non-thermal microplasma for the synthesis of aqueous gold nanoparticles (AuNPs). The microplasma-induced liquid chemistry was analyzed by monitoring the pH value and the conductivity of the liquid. Morphology and optical properties of the synthesized AuNPs were characterized by transmission electron microscopy (TEM) and ultraviolet-visible (UV-VIS) spectroscopy. We found that the size distribution of AuNPs can be tailored by altering the process parameters (stirring mode, discharge power, and concentration of sodium citrate in the liquid). The synthesized AuNPs were used to detect cardiac troponin I (cTn-I) based on lateral flow immune-chromatography assays (LFIA). Test strips prepared by microplasma-generated AuNPs showed an increased sensitivity compared to strips prepared by AuNPs produced by conventional chemical reduction. This might be attributed to an increased negative charge density on the surfaces of the microplasma-gener-atedAuNPs.

This paper presents a one‐step method for the rapid synthesis of colloidal silver nanoparticles (AgNPs) for bacterial disinfection. Silver ions were electrochemically reduced to silver atoms in an AgNO3 solution with the assistance of an atmospheric argon microplasma jet. Dextran was used to stabilize the AgNPs in the liquid solution. Ultraviolet–visible spectroscopy, transmission electron microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy were used to characterize the synthesized AgNPs. It was found that the size of the nanoparticles can be controlled by adjusting the dextran monomer/Ag+ molar ratio in the solution. Furthermore, antibacterial activity of the as‐synthesized AgNPs against Escherichia coli and Staphylococcus aureus was carried out in liquid as well as on solid growth media, as a function of the AgNPs concentration. The results showed that the AgNPs had a significant antibacterial activity against those bacteria cells and the minimum inhibition concentration was associated with the type of bacteria and initial bacterial concentration.

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Here, we present a novel approach for producing Fe 3 O 4 nanoparticles (NPs) in liquid by a nonthermal argon microplasma. The Fe 3 O 4 NPs can be generated in minutes without any surfactant with an average size of 12.5 AE 2.4 nm. They show good aqueous-phase stability and excellent superparamagnetic properties with a saturation magnetization of 60.1 emu g À1 and a small coercivity (<10 Oe). In vitro magnetic resonance imaging study shows efficient imaging contrast characteristics of these NPs. These Fe 3 O 4 NPs can be further decorated with polyethylene glycol (PEG) by adding 5% PEG into the electrolyte, which resulting in an average diameter of 19.2 AE 2.7 nm. This facile, fast, environmentalfriendly and economical preparation strategy of magnetite NPs may be extended to the preparation of other metal oxide compound.

A waveguide Bragg grating (WBG) provides a flexible way for measurement, and it could even be used to measure body temperature like e-skin. We designed and compared three structures of WBG with the grating period, etching depth, and duty cycle. The two-sided WBG was fabricated. An experimental platform based on photonic integrated interrogator was set up and the experiment on the two-sided WBG was performed. Results show that the two-sided WBG can be used to measure temperature changes over the range of 35–42 °C, with a temperature measurement error of 0.1 °C. This approach has the potential to facilitate application of such a silicon-on-insulator (SOI) WBG photonic sensor to wearable technology and realize the measurement of human temperature.